UPS 2 backpay - does it exist?

Hi,
I have today (24th Feb) been told that I have been approved to progress to UPS 2. My head has been off with stress and performance management meetings weren't held until January. I raised the issue of progression then, a further meeting was planned, OFSTED intervened and we haven't done it until today. My simple question is: does UPS 2, like UPS 1, come into effect from the start of the year it is awarded i.e. for me, September 2011? Or does is just begin when it is agreed? I have delved somewhat into legislation and haven't found any answers yet.
In other words, do they owe me any back pay or not?
Hope so! Thanks for your help.